This invention relates to an integrated pump and tappet unit for a fuel feeding system of an internal combustion engine.
Large diesel engines refer here to such engines that are applicable for instance for main propulsion engines or auxiliary engines for ships or for power plants for production of heat and/or electricity.
In order to accomplish fuel injection under high pressure into a cylinder of an engine a high pressure pump is needed as well as phasing of the operation of the pump according to the operating cycle of the cylinder, which can be accomplished by means of a tappet member controlled by a cam shaft or the like member of the engine. In so-called common pressure or common rail systems and their applications this kind of phasing is not necessary, but nevertheless the operation of the pump may be controlled by means of corresponding members. In accordance with known techniques the pump and the tappet are arranged to be entirely separate units. In this case a separate lubrication is arranged for the pump, whereby fuel, especially heavy oil utilized in modern engines, cannot enter the tappet unit, in which it could be mixed with the lubrication oil. The pump and tappet then each need, however, a body of their own, which increases the manufacturing costs and requires more space.
It is further known to connect the pump and the tappet to each other, which makes the construction simpler and decreases the manufacturing costs. However, in known solutions in which the pump and tappet are connected together, mixing of the fuel with the lubrication oil is possible, as a consequence of which the quality of the lubrication oil decreases and affects the whole circulation of lubricant. This may result in the pump and the tappet becoming stuck and may even result in damage of various kinds to the bearings, including the crank shaft bearings.